Magnetic head and disk device having the same

ABSTRACT

A magnetic head includes a main magnetic pole, a write shield separated from the main magnetic pole by a write gap, a first side shield that is separated from the main magnetic pole by a first side gap, a second side shield that is separated from the main magnetic pole by a second side gap, a first layer that has a first magnetic relative permeability and is disposed in the write gap between the main magnetic pole and the write shield, and a second layer that has a second magnetic relative permeability and is disposed in the first side gap and the second side gap, wherein the first magnetic relative permeability is smaller than the second magnetic relative permeability.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.15/902,531, filed Feb. 22, 2018, which application is based upon andclaims the benefit of priority from Japanese Patent Application No.2017-164490, filed Aug. 29, 2017, the entire contents of which areincorporated herein by reference.

FIELD

Embodiments described herein relate generally to a magnetic head and adisk device having the same.

BACKGROUND

A magnetic disk drive includes a disk-shaped recording medium disposedin a casing, that is, a magnetic disk and a magnetic head that reads andwrites information from/to the magnetic disk. The magnetic headincludes, for example, a recording head and a read head (reproducingelement). The recording head includes a main magnetic pole thatgenerates a recording magnetic field, a write shield, and side shieldsthat face each other with a gap between the main magnetic pole.

In such a recording head, recording resolution (recording density) islargely influenced by a distance (gap length) between the main magneticpole and the shield. With increasing recording density, the gap lengthtends to become smaller. However, when the gap length becomes smaller,the write shield can be magnetically saturated due to the magnetic fieldgenerated from the main magnetic pole. As a result, the write shielddoes not function effectively as a shield. In this case, the recordingresolution and the recording density of the recording head are adverselyaffected.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically illustrating a hard disk drive(HDD) according to a first embodiment;

FIG. 2 is a side view illustrating a magnetic head, a suspension, and amagnetic disk in the HDD;

FIG. 3 is an enlarged cross-sectional view of a head portion of themagnetic head;

FIG. 4 is a partial cross-sectional perspective view illustrating themain components of a recording head in the magnetic head;

FIG. 5 is an enlarged cross-sectional view of the recording head of FIG.4 illustrating a tip end of the recording head;

FIG. 6 is a plan view of the recording head as viewed from an ABS;

FIG. 7 is a diagram illustrating a relation between a gap length and arecording density for the recording head and a magnetic head accordingto a comparative example;

FIG. 8 is a plan view of a magnetic head according to a secondembodiment as viewed from the ABS;

FIG. 9 is a plan view of a magnetic head according to a third embodimentas viewed from the ABS; and

FIG. 10 is an enlarged cross-sectional view illustrating a tip end ofthe magnetic head according to the third embodiment.

DETAILED DESCRIPTION

According to embodiments provided herein, a magnetic recording head iscapable of preventing saturation of a shield and improving a recordingdensity. A magnetic disk device having such a magnetic recording head isalso described.

In general, according to one embodiment, a magnetic head includes a mainmagnetic pole that generates a recording magnetic field, a write shielddisposed adjacent to the main magnetic pole and separated from the mainmagnetic pole by a write gap, a first side shield that is disposed on afirst side of the main magnetic pole in a track width direction from themain magnetic pole and is separated from the main magnetic pole by afirst side gap, a second side shield that is disposed on a second sideof the main magnetic pole in the track width direction from the mainmagnetic pole and is separated from the main magnetic pole by a secondside gap, a first layer that has a first magnetic relative permeabilityand is disposed in the write gap between the main magnetic pole and thewrite shield, and a second layer that has a second magnetic relativepermeability and is disposed in the first side gap and the second sidegap, wherein the first magnetic relative permeability is smaller thanthe second magnetic relative permeability.

With reference to the drawings, disk devices according to embodimentswill be described.

Note that the disclosure is merely an example, and any modification andvariation which can be easily conceived by a person ordinarily skilledin the art without departing from the spirit of the embodimentsnaturally falls within the scope of the present invention. To furtherclarify explanation, for example, the width, thickness, or shape of eachstructure may be schematically shown in the drawings, and are not toscale. Note that the drawings are merely examples and do not limit theinterpretation of the present invention. In the specification anddrawings, elements which are identical to previously-described elementsare denoted by the same reference numbers. Thus, the detailedexplanation of such elements may be omitted.

First Embodiment

A hard disk drive (HDD) according to an embodiment will be described indetail. FIG. 1 is a block diagram schematically illustrating an HDDaccording to a first embodiment, and FIG. 2 is a side view illustratinga flying state of a magnetic head and a magnetic disk of the HDD.

As illustrated in FIG. 1, an HDD 10 is a disk device that includes arectangular housing 11, a magnetic disk 12 as a recording mediumdisposed in the housing 11, a spindle motor 21 supporting and rotatingthe magnetic disk 12, and a plurality of magnetic heads 16 configured towrite/read data on/from the magnetic disk 12. Further, the HDD 10includes a head actuator 18 that moves each magnetic head 16 onto anarbitrary track on the magnetic disk 12 for positioning. The headactuator 18 includes a carriage assembly 20 configured to movablysupport the magnetic heads 16 and a voice coil motor (VCM) 22 configuredto rotate the carriage assembly 20.

The HDD 10 includes a head amplifier IC 30, a main controller 32 and adriver IC 37. The head amplifier IC 30 is disposed on, for example, thecarriage assembly 20, and is electrically connected to the magnetic head16. For example, the main controller 32 and driver IC 37 can be formedon a control circuit board (not illustrated) disposed on a back surfaceside of the housing 11. The main controller 32 includes an R/W channel33, a hard disk controller (HDC) 34, and a microprocessor (MPU) 36. Themain controller 32 is electrically connected to the magnetic heads 16via the head amplifier IC 30. The main controller 32 is alsoelectrically connected to the VCM 22 and spindle motor 21 via the driverIC 37. The HDC 34 is connectable to a host computer 38.

As illustrated in FIGS. 1 and 2, the magnetic disk 12 is a perpendicularmagnetic medium. The magnetic disk includes a substrate 101 formed of anonmagnetic substance and in the shape of a disc having a diameter ofapproximately 2.5 inches (6.35 cm), for example. On each surface of thesubstrate 101, a soft magnetic layer 102, a perpendicular magneticrecording layer 103, and a protection film 104, are sequentially stackedin this order. The soft magnetic layer 102 is an under layer made of amaterial exhibiting soft magnetic characteristics, and the perpendicularmagnetic recording layer 103 has magnetic anisotropy in a directionperpendicular to the surface of the magnetic disk 12. The magnetic disk12 is coaxially fitted to a hub of the spindle motor 21. The magneticdisk 12 is rotated in a direction of the arrow B at a predeterminedspeed by the spindle motor 21.

The carriage assembly 20 includes a bearing unit 24 rotatably fixed tothe housing 11 and a plurality of suspensions 26 extending from thebearing unit 24. As illustrated in FIG. 2, each of the magnetic heads 16is supported on an extendable end of each suspension 26. Each of themagnetic heads 16 is electrically connected to the head amplifier IC 30via a wiring member 28 disposed on the carriage assembly 20.

As illustrated in FIG. 2, each of the magnetic heads 16 is formed as aflying head, and includes a slider 42 formed in a substantiallyrectangular parallelepiped shape and a writing/reading head portion 44formed at an end of a downstream (i.e., trailing) side of the slider 42.The slider 42 is formed of, for example, a sintered body of alumina andtitanium carbide (AlTiC). The head portion 44 is formed to include aplurality of thin films that are stacked on each other. The magnetichead 16 is fixed to a gimbal spring 41 disposed at a tip end of thesuspension 26.

The slider 42 has a rectangular disk-facing surface (recordingmedium-facing surface or air bearing surface (ABS)) 43 facing thesurface of the magnetic disk 12. The slider 42 floats over the surfaceof the magnetic disk 12 by a predetermined amount by airflow C presentbetween the surface of the disk and the ABS 43 that is due to therotation of the magnetic disk 12. A direction of the airflow C coincideswith a rotation direction B of the magnetic disk 12. The slider 42includes a leading end 42 a located on an upstream side of the airflowC, and a trailing end 42 b located on a downstream side of the airflowC. During rotation of the magnetic disk 12, the magnetic head 16 travelsin a direction of the arrow A (i.e., the head traveling direction) withrespect to the magnetic disk 12, that is, in a direction opposite to therotation direction B of the magnetic disk 12.

FIG. 3 is an enlarged cross-sectional view illustrating the head portion44. As illustrated in FIG. 3, the head portion 44 includes a reproducinghead (read head) 54 and a recording head (write head) 58 which areformed on the trailing end 42 b of the slider 42 by a thin-film processand are formed as a separable magnetic head. The read head 54 and thewrite head 58 are covered with a non-magnetic protective insulating film76 except a portion exposed to the ABS 43 of the slider 42. Theprotective insulating film 76 is formed on surfaces of or is included inthe head portion 44.

The read head 54 includes a magnetic film 55 having magnetoresistanceand shield films 56 and 57. The shield film 57 is disposed on thetrailing side of the magnetic film 55 and the shield film 56 is disposedon the leading side of the magnetic film 55, so as to sandwich themagnetic film 55. Lower ends of magnetic film 55 and the shield films 56and 57 are exposed on the ABS 43 of the slider 42 as shown.

The write head 58 is disposed on the trailing end 42 b of the slider 42relative to the read head 54. FIG. 4 is a partial cross-sectionalperspective view illustrating the main components of the recording head,FIG. 5 is an enlarged cross-sectional view illustrating a tip end 60a ofthe write head 58, and FIG. 6 is an enlarged plan view illustrating thewrite head 58 as viewed from the ABS 43.

As illustrated in FIGS. 3 and 4, the write head 58 includes a mainmagnetic pole 60 made of a high saturation magnetic flux densitymaterial, a trailing shield (write shield) 62 made of a soft magneticmaterial, a pair of side shields 63, and a leading shield 64. The mainmagnetic pole 60 generates a recording magnetic field in a directionperpendicular to the surface of the magnetic disk 12. The trailingshield 62 is disposed with a write gap WG (which is a gap length in adown-track direction D) on the trailing side of the main magnetic pole60, and is included in the write head 58 to facilitate closure of amagnetic path via the soft magnetic layer 102 in the magnetic disk 12directly below the main magnetic pole 60. The pair of side shields 63are positioned to face each other with side gaps SG on both sidesurfaces of the main magnetic pole 60 in a track width direction TW.

Specifically, for each side shield 63, a side gap SG is disposed betweena side surface 63 b of the side shield and a corresponding side surface60 e of the main magnetic pole 60, where the side gap SG separated theside shield 63 from the main magnetic pole 60 in the track widthdirection TW. Furthermore, the leading shield 64 is positioned so that agap (not labeled) is disposed between the leading shield 64 and the mainmagnetic pole 60 on the leading side of the main magnetic pole 60.Similarly, the trailing shield 62 is positioned so that the write gap WGis disposed between the trailing shield 62 and the main magnetic pole 60on the trailing side of the main magnetic pole 60. In the firstembodiment, the side shields 63 and the leading shield 64 may beintegrally formed as a single component of a soft magnetic material. Theleading shield has an L-shape with a lower end 64 a that extends in adirection towards the tip end 62 a of the trailing shield 62.

The trailing shield 62 is formed in a substantially L-shape (when viewedfrom the side as in FIG. 4) and has a first connection portion 50 (shownin FIGS. 3 and 4) coupled to the main magnetic pole 60. The firstconnection portion 50 is coupled via a nonconductor 52 to an upper partof the main magnetic pole 60, that is, an upper part of the mainmagnetic pole 60 that is positioned farther away from the disk-facingsurface 43 than another part of the main trailing shield 60. The leadingshield 64 has a first connection portion 68 that is coupled to the mainmagnetic pole 60 via a nonconductor (insulator) 69 at a location that isfarther away from the magnetic disk 12 than another part of the leadingshield 64. The first connection portion 68 is formed of, for example, asoft magnetic material, and forms a magnetic circuit together with themain magnetic pole 60 and the leading shield 64. In addition, at thelocation of the first connection portion 68, the main magnetic pole 60and the leading shield 64 are electrically insulated from each other bythe insulator 69.

The write head 58 includes a first recording coil 70 and a secondrecording coil 72 for allowing a magnetic flux to flow to the mainmagnetic pole 60. The first recording coil 70 is wound around a firstmagnetic core including the main magnetic pole 60 and the trailingshield 62, and the second recording coil 72 is wound around a secondmagnetic core including the main magnetic pole 60 and the leading shield64. The first recording coil 70 and the second recording coil 72 areconnected to terminals 95 and 96, respectively, and these terminals 95and 96 are connected to a recording current circuit 97. The secondrecording coil 72 is connected to the first recording coil 70 in series.When a signal is written to the magnetic disk 12, a predeterminedcurrent is supplied to the first recording coil 70 and the secondrecording coil 72 from the recording current circuit 97, whereby amagnetic flux flows to the main magnetic pole 60 and a magnetic field isgenerated.

As illustrated in FIGS. 3 to 6, the main magnetic pole 60 extendssubstantially perpendicularly to the surface of the magnetic disk 12 andthe ABS 43. The tip end 60 a of the main magnetic pole 60, which isformed on the ABS 43 end of the main magnetic pole 60, is taperednarrowly (in a funnel shape) toward the ABS 43. The tip end 60 a of themain magnetic pole 60 includes a trailing-side surface 60 c located onthe trailing side of the main magnetic pole 60, a leading-side surface60 d opposite to the trailing-side end surface, and the two sidesurfaces 60 e (the latter are shown in FIG. 6). The leading-side surface60 d is located on the leading side of the main magnetic pole 60. Asurface of the tip end 60 a of the main magnetic pole 60 is exposed tothe ABS 43 of the slider 42. In the tip end 60 a, the trailing-sidesurface 60 c extends obliquely away from ABS 43 with respect to adirection perpendicular to the ABS 43, as shown in FIG. 5. Similarly, toform the narrowly tapered funnel shape of tip end 60 a, both sidesurfaces 60 e extend obliquely away from ABS 43 with respect to adirection perpendicular to the ABS 43, and also with respect to acentral axis of the main magnetic pole 60. That is, both side surfaces60 e extend obliquely away from ABS 43 in the track width direction TW.

A tip end 62 a of the trailing shield 62 is formed in a slenderrectangular shape in cross section, and has an extended tip portion 65,as shown in FIGS. 3 and 4. A lower end surface of the trailing shield 62is exposed to the ABS 43 of the slider 42, as shown in FIGS. 5 and 6. Aleading-side surface 62 b of the tip end 62 a extends along (i.e.,substantially parallel to) the track width direction TW, and is thesurface of tip end 62 a that faces the main magnetic pole 60. Theleading-side surface 62 b extends away from the ABS 43 and obliquelywith respect to the direction perpendicular to the ABS 43, as shown inFIG. 5. The write gap WG is disposed between the leading-side surface 62b of the tip end 62 a of the trailing shield 62 and the trailing-sidesurface 60 c of the tip end 60 a of the main magnetic pole 60. Inaddition, the leading-side surface 62 b of the tip end 62 a issubstantially parallel to the trailing-side surface 60 c of the tip end60 a. The trailing-side surface 60 c of the main magnetic pole 60 andthe leading-side surface 62 b of the trailing shield 62 may extend inthe direction perpendicular to the ABS 43 (i.e., out of the page in FIG.5 and in FIG. 6).

In the first embodiment, the pair of side shields 63 are formed from thesame soft magnetic material as the leading shield 64, and are formedintegrally with the leading shield 64 as a single body. In addition, thepair of side shields 63 extend from the leading shield 64 toward thetrailing shield 62, as shown in FIG. 6. Thus, the side shields 63 aredisposed between leading shield 64 and the trailing shield 62, in thedown-track direction D. Each of the pair of side shields 63 isphysically separated via a side gap SG from the main magnetic pole 60 onone side of the main magnetic pole 60 in the track width direction TW,and are magnetically and electrically coupled to the leading shield 64.Specifically, one of the side shields 63 is separated from the mainmagnetic pole 60 by one side gap SG and the other of the side shields 63is separated from the main magnetic pole 60 by the other side gap SG, asshown in FIG. 6. For each of the side shields, a side surface 63 b ispositioned substantially in parallel with a corresponding side surface60 e of the main magnetic pole 60 with a gap SG therebetween. A tip endsurface of the side shield 63 is exposed and forms a portion of the ABS43.

As illustrated in FIGS. 5 and 6, a protective insulating film 73 isdisposed in a space between the main magnetic pole 60 and the tip end 62a of the trailing shield 62, in a space between the main magnetic pole60 and the leading shield 64, and in a space between the main magneticpole 60 and the side shields 63. The protective insulating film 73 ismade of a non-magnetic insulator, for example, alumina or silicon oxide.

In the first embodiment, a non-magnetic or magnetic first layer 80 isfilled in the write gap WG between the main magnetic pole 60 and thetrailing shield 62. Additionally, a non-magnetic or magnetic secondlayer 82 is disposed within and fills the side gap SG between the mainmagnetic pole 60 and each of the side shields 63. Magnetic relativepermeability A of the first layer 80 is smaller than the magneticrelative permeability B of the second layer 82, and is set to satisfythe relation of A<B, where magnetic relative permeability is the measureof the ability of a material to support the formation of a magneticfield within itself. Furthermore, the difference between the magneticrelative permeability A of the first layer 80 and the magnetic relativepermeability B of the second layer 82 is preferably 2 or more. The firstlayer 80 can be formed using, for example, Fe, Co, or Ni. The secondlayer 82 can be formed using, for example, Fe, Co, or Ni.

According to the magnetic head 16 configured as described above, thefirst layer 80 and the second layer 82 for satisfying the relation ofthe magnetic relative permeability A<B are disposed between the shieldsof the write head 58, thereby adjusting a magnetic flux flowing towardthe side shield 63 during the magnetic recording. That is, the smallermagnetic relative permeability of layer 80 relative to the magneticrelative permeability of layer 82 adjusts the magnetic flux to activelyflow toward the side shield 63. Thus, even when the write gap WG betweenthe main magnetic pole 60 and the trailing shield 62 becomes narrow, itis possible to reduce the magnetic flux flowing directly from the mainmagnetic pole 60 toward the write shield 62 and to prevent magneticsaturation of the write shield 62. Accordingly, it is possible toimprove a recording density while maintaining the functionality of thewrite shield 62 as a magnetic shield.

FIG. 7 illustrates results obtained by measuring a relation between alength of the write gap WG and a recording density (resolution) (such asbits per inch, or BPI) in the down-track direction D for the magnetichead according to the first embodiment and a magnetic head according toa comparative example. The magnetic head of the comparative example is aconventional magnetic head that does not include the first layer 80 andthe second layer 82. That is, the magnetic head of the comparativeexample is a magnetic head in which the protective insulating film isdisposed over the entire gap between the main magnetic pole and thewrite shield.

As illustrated in FIG. 7, for the magnetic head of the comparativeexample, as the distance (write gap WG) between the main magnetic poleand the trailing shield becomes narrow, the recording density can beimproved up to a certain distance, but then, as the trailing shield issaturated, the recording density can decreases. That is, when the writegap WG is too narrow, the trailing shield is magnetically saturated andthe recording density that is possible for the magnetic head of thecomparative example deteriorates.

In contrast, according to the magnetic head of the first embodiment, itis understood that even when the distance (write gap WG) between themain magnetic pole and the trailing shield becomes narrow, the recordingdensity continues to improve. This is because the magnetic flux can bereleased to the side shield, the trailing shield does not becomemagnetically saturated, and the recording density can be improved.

In light of the above, according to the first embodiment, it is possibleto obtain a magnetic recording head capable of preventing the saturationof the shield and improving the recording density and a magnetic diskdevice having such a magnetic recording head.

As long as the first layer and the second layer of the recording headhave magnetic relative permeabilities that satisfy the relation:magnetic relative permeability A<B, any suitable materials other thanthe materials described in the first embodiment can be selected for thefirst layer and second layer.

Magnetic heads and disk devices according to other embodiments will bedescribed below. In the embodiments described below, the same referencenumerals are given to similar components already described in the firstembodiment, and the detailed description thereof is simplified oromitted. The components different from those of the first embodimentwill be described in detail.

Second Embodiment

FIG. 8 is a plan view of a recording head according to a secondembodiment, in which a tip end of the recording head and an ABS of therecording head are viewed. In the second embodiment, a first layer 80 isdisposed between a main magnetic pole 60 and a trailing shield 62 of awrite head 58 and fills a write gap WG. In the second embodiment, thefirst layer 80 is formed with the same layer as a surrounding protectiveinsulating film 73 and has a magnetic relative permeability A of 1. Asecond layer 82 fills a side gap SG between the main magnetic pole 60and each of side shields 63, and is formed of a magnetic layer or a weakmagnetic layer having a magnetic relative permeability B that is greaterthan 1. The second layer 82 can be formed using, for example, Fe, Co, orNi. The difference between the magnetic relative permeability A of thefirst layer 80 and the magnetic relative permeability B of the secondlayer 82 is preferably 2 or more. In the second embodiment, otherconfigurations of the write head 58 and other configurations of themagnetic head are similar to those of the first embodiment describedabove.

According to the magnetic head configured as described above, the firstlayer 80 and the second layer satisfy the relation of the magneticrelative permeability A<B, and are disposed between the shields of thewrite head 58 as shown in FIG. 8. As a result, a magnetic flux flowingtoward the side shield 63 during magnetic recording is increased. Thus,even when the write gap WG between the main magnetic pole 60 and thetrailing shield 62 becomes narrow, it is possible to reduce the magneticflux flowing directly from the main magnetic pole 60 toward write shield62, thereby preventing magnetic saturation of the write shield 62.Accordingly, it is possible to improve a recording density that can beattained by the write head 58 while maintaining a shield function of thewrite shield 62.

Third Embodiment

FIG. 9 is a plan view of a recording head according to a thirdembodiment, in which a tip end of the recording head and an ABS of therecording head are viewed, and FIG. 10 is a cross-sectional viewillustrating the tip end of the recording head according to the thirdembodiment.

In the third embodiment, a first layer 80 is disposed in and fills awrite gap WG between a main magnetic pole 60 and a trailing shield 62 ofa write head is used as a magnetic flux control layer, where the firslayer includes a plurality of stacked conductive layers. The magneticflux control layer includes, for example, a first control layer 80 a, asecond control layer 80 b, and a third control layer 80 c that aresequentially stacked from the main magnetic pole 60 toward the trailingshield 62. The first control layer 80 a can be formed using a material,for example, Cu, Au, Ag, Al, Ir, or an NiAl alloy which has a metalphase and does not interfere with spin conduction. The second controllayer 80 b can include a metal layer and be formed using a magneticmetal selected from the group consisting of Fe, Co, and Ni and a softmagnetic metal alloy containing at least one of Fe, Co, and Ni. Thethird control layer 80 c can be formed using a material which isnon-magnetic metal and blocks spin conduction. Specifically, the thirdcontrol layer 80 c can be formed of at least one selected from the groupconsisting of Ta, Ru, Pt, W, and/or Mo or an alloy containing at leastone of thereof. The first control layer 80 a and the third control layer80 c may also be swapped in position and therefore stacked in reverseorder to that shown in FIG. 10.

A tip end 60 a of the main magnetic pole 60 and a tip end 62 a of thetrailing shield 62 are electrically connected to each other via themagnetic flux control layer 80.

A second layer 82 is filled in a side gap SG between the main magneticpole 60 and each of side shields 63. The second layer 82 can be formedusing, for example, alumina.

As illustrated in FIG. 10, connection terminals 90 and 91 are connectedto the main magnetic pole 60 and the trailing shield 62, respectively,so that a current I flows through the main magnetic pole 60 and thetrailing shield 62. A controller of the HDD has a power supply 94connected to the connection terminals 90 and 91. An electric circuit isformed in which a current flows through the connection terminal 90, themain magnetic pole 60, the magnetic flux control layer 80, the trailingshield 62, and the connection terminal 91.

When the current flows to the magnetic flux control layer 80 from thepower supply 94 via the main magnetic pole 60 and the trailing shield62, the magnetic flux control layer 80 generates a magnetic flux in adirection opposite that of the magnetic flux from the main magnetic pole60 to the trailing shield 62. As a result, the magnetic relativepermeability A of the magnetic flux control layer 80 is lower than themagnetic relative permeability of air, and substantially lower thanmagnetic relative permeability B of the second layer 82. Accordingly,the magnetic relative permeability satisfies the relation of A<B.

In the third embodiment, other configurations of the write head 58 andthe magnetic head are similar to those of the magnetic head and therecording head in the first embodiment described above. In the thirdembodiment, a magnetic flux flowing toward the side shield 63 during themagnetic recording is also increased. Thus, even when the write gap WGbetween the main magnetic pole 60 and the trailing shield 62 is narrow,it is possible to reduce the magnetic flux flowing directly from themain magnetic pole toward write shield 62 and to prevent magneticsaturation of the write shield 62. Accordingly, it is possible toimprove a recording density of the write head 58 while maintaining themagnetic shield functionality of the write shield 62.

The magnetic flux control layer can be formed by selecting variousmaterials other than the materials in the embodiments described above.The magnetic flux control layer has the configuration in which threelayers are stacked, but may have a configuration in which two layers orfour or more layers are stacked.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

For example, in some embodiments, the leading shield can be omitted inthe magnetic recording head. The materials, shapes, and sizes of thecomponents of the disk device are described in the above embodiment, butcan also be changed in various way as appropriate.

What is claimed is:
 1. A magnetic head comprising: a main magnetic polethat generates a recording magnetic field; a write shield disposedadjacent to the main magnetic pole and separated from the main magneticpole by a write gap; a first side shield that is disposed on a firstside of the main magnetic pole in a track width direction from the mainmagnetic pole and is separated from the main magnetic pole by a firstside gap; a second side shield that is disposed on a second side of themain magnetic pole in the track width direction from the main magneticpole and is separated from the main magnetic pole by a second side gap;a first layer that has a first magnetic relative permeability and isdisposed in the write gap between the main magnetic pole and the writeshield; and a second layer that has a second magnetic relativepermeability and is disposed in the first side gap and the second sidegap, wherein the first magnetic relative permeability is smaller thanthe second magnetic relative permeability, the first layer includes amagnetic flux control layer in which a plurality of conductive layersare stacked, the magnetic flux control layer having a magnetic relativepermeability smaller than that of air when a current flows through themagnetic flux control layer.
 2. The magnetic head according to claim 1,further comprising: a connection terminal that is configured to flow thecurrent through the main magnetic pole, the magnetic flux control layer,and the write shield.
 3. The magnetic head according to claim 1, whereinthe magnetic flux control layer includes a first control layercontaining at least one element selected from the group consisting ofFe, Co, and Ni and a second control layer containing at least oneelement selected from the group consisting of Cu, Ag, and Au and stackedon the first control layer.
 4. The magnetic head according to claim 1,wherein the main magnetic pole and the write shield are electricallyconnected to each other via the magnetic flux control layer.
 5. A diskdevice comprising: a disk-shaped recording medium; and a magnetic headcomprising: a main magnetic pole that generates a recording magneticfield; a write shield disposed adjacent to the main magnetic pole andseparated from the main magnetic pole by a write gap; a first sideshield that is disposed on a first side of the main magnetic pole in atrack width direction from the main magnetic pole and is separated fromthe main magnetic pole by a first side gap; a second side shield that isdisposed on a second side of the main magnetic pole in the track widthdirection from the main magnetic pole and is separated from the mainmagnetic pole by a second side gap; a first layer that has a firstmagnetic relative permeability and is disposed in the write gap betweenthe main magnetic pole and the write shield; and a second layer that hasa second magnetic relative permeability and is disposed in the firstside gap and the second side gap, wherein the first magnetic relativepermeability is smaller than the second magnetic relative permeability,and the first layer includes a magnetic flux control layer in which aplurality of conductive layers are stacked, the magnetic flux controllayer having a magnetic relative permeability smaller than that of airwhen a current flows through the magnetic flux control layer.
 6. Thedisk device according to claim 5, wherein the magnetic flux controllayer includes a first control layer containing at least one elementselected from the group consisting of Fe, Co, and Ni and a secondcontrol layer containing at least one element selected from the groupconsisting of Cu, Ag, and Au and stacked on the first control layer. 7.The disk device according to claim 5, wherein the main magnetic pole andthe write shield are electrically connected to each other via themagnetic flux control layer.